diff --git a/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php b/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php
index 4403384909..4ac4b18895 100644
--- a/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php
+++ b/src/Symfony/Component/Config/Definition/Builder/ArrayNodeDefinition.php
@@ -307,7 +307,7 @@ class ArrayNodeDefinition extends NodeDefinition implements ParentNodeDefinition
 
             if (false !== $this->addDefaultChildren) {
                 $node->setAddChildrenIfNoneSet($this->addDefaultChildren);
-                if ($this->prototype instanceof static) {
+                if ($this->prototype instanceof static && null === $this->prototype->prototype) {
                     $this->prototype->addDefaultsIfNotSet();
                 }
             }
diff --git a/tests/Symfony/Tests/Component/Config/Definition/Builder/ArrayNodeDefinitionTest.php b/tests/Symfony/Tests/Component/Config/Definition/Builder/ArrayNodeDefinitionTest.php
index 9639b94a2f..35d62a8b3e 100644
--- a/tests/Symfony/Tests/Component/Config/Definition/Builder/ArrayNodeDefinitionTest.php
+++ b/tests/Symfony/Tests/Component/Config/Definition/Builder/ArrayNodeDefinitionTest.php
@@ -89,6 +89,17 @@ class ArrayNodeDefinitionTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals(array(array()), $tree->getDefaultValue());
     }
 
+    public function testNestedPrototypedArrayNodes()
+    {
+        $node = new ArrayNodeDefinition('root');
+        $node
+            ->addDefaultChildrenWhenNoneSet()
+            ->prototype('array')
+                  ->prototype('array')
+        ;
+        $tree = $node->getNode();
+    }
+
     protected function getField($object, $field)
     {
         $reflection = new \ReflectionProperty($object, $field);